And I'm Renee Montagne. We come to you this morning with grim news. The U.S. ambassador to Libya and three other Americans have been killed when protesters stormed the U.S. consulate in Benghazi. The protests were sparked yesterday by an American-made video circulating on the Web that ridicules Islam and the prophet Muhammad.

Moments ago, Secretary of State Hillary Clinton spoke of Ambassador John Christopher Stevens and the other men who died. Of him she said he made Libya's hopes his hopes.

SECRETARY HILLARY CLINTON: In the lobby of this building, the State Department, the names of those who have fallen in the line of duty are inscribed in marble. Our hearts break over each one, and now, because of this tragedy, we have new heroes to honor and more friends to mourn.

KELEMEN: Well, he was a 21-year veteran of the foreign service. He served in many places in the Middle East before taking this job as ambassador in Libya, and in fact he played a key role in shaping U.S. policy during the uprising against Moammar Gadhafi. Ambassador Chris Stevens was then the U.S. envoy to the opposition in Benghazi, and as Secretary Clinton said in her very emotional statement just now, he risked his life trying to stop a tyrant and he died trying to help this new nation.

So she's asking the questions that many in the State Department family are raising today: How could this happen in a country that we all helped liberate and in a city that we helped save? That was - those were her words this morning.

MONTAGNE: Well, let me ask you something about that then. You know, how could it happen? Apparently there's this video. It sparked protests also in Cairo, which did not end in - did not turn deadly, certainly. What are the Libyans saying and what is the State Department saying about the protests?

KELEMEN: Secretary Clinton pointed out that Libyans and U.S. security forces tried to fight back what she called this small and savage group of protesters. The Libyans say that it was not only a protest against this video but that there were supporters of the ousted leader, Moammar Gadhafi, that got involved in this attack.

Clinton spoke last night with the president of Libya and she said he also condemned the attack, and she said we won't rest until we find those who are responsible.

MONTAGNE: And of course we have yet to know really what all the facts are that led to these deaths. What do you know about the other Americans who were killed?

KELEMEN: Secretary Clinton identified one of them as a foreign service information management officer. His name is Sean Smith. He joined the State Department 10 years ago and served in Baghdad, Pretoria, Montreal and the Hague. Sorry. And Clinton said that he's a husband and a father of two. She did not name the other two Americans who were killed in this attack, as she's still notifying the next of kin.

MONTAGNE: And this is stunning in the sense that it has been a very long time since a U.S. ambassador was killed. The last time, I gather, was in Afghanistan. So this is very rare.

KELEMEN: That's true. According to the State Department's office, the historian, there have been five U.S. ambassadors killed by terrorists, dating back from 1968 up to 1979. So this has been a real shock to the State Department.

MONTAGNE: And we will, of course, be bringing our listeners more as we learn it. NPR's Michele Kelemen, thank you very much.